The invention relates to molecular fluorine lasers emitting around 157 nm. The emitting molecular fluorine laser oscillator followed by an amplifier for increasing the energy of the emitted laser beam to a desired power for applications processing.
The oscillator-amplifier design provides a laser beam at desired energies for application processing such as photolithography. Use of the design set forth also involves synchronization of two laser systems, i.e., the oscillator and the amplifier, in parallel, which can be expensive, can tend to occupy a lot of space and may be unreliable under certain circumstances. Preliminary experiments have shown that the oscillator-amplifier stage can provide an advantageous 157 nm laser beam for application processing. However, the design may also present, in some circumstances, a competitively disadvantageous economic solution relative to systems which would use the natural bandwidth of emission of the F2 laser for use with an imaging system having a catadioptric lens design. It is therefore an object of the present invention to provide a more compact, economic molecular fluorine laser system which emits a beam around 157 nm having a narrow bandwidth and sufficient power for application processing.
In view of the above object, a molecular fluorine (F2) laser system is provided including a power amplifier. The oscillator includes a laser tube including multiple electrodes therein which are connected to a discharge circuit. The laser tube is part of an optical resonator for generating a laser beam including a first line of multiple characteristic emission lines around 157 nm. The laser tube is filled with a gas mixture including molecular fluorine and a buffer gas. The gas mixture is at a pressure that can be below that which results in the generation of a laser emission including the first line around 157 nm having a natural linewidth of less than 0.5 pm without an additional line-narrowing optical component for narrowing the first line. The power amplifier increases the power of the beam emitted by the oscillator to a desired power for applications processing.
A molecular fluorine laser system is also provided including a discharge tube filled with a gas mixture including molecular fluorine and a buffer gas, multiple electrodes within the discharge chamber connected to a discharge circuit for energizing the gas mixture, a resonator for generating a laser beam including a first line of multiple characteristic emission lines around 157 nm, and a power amplifier for increasing the power of the beam generated by the resonator to a desired power for applications processing. The gas mixture has a total pressure which is sufficiently low such that the laser beam includes the first line around 157 nm having a linewidth of less than 0.5.
A molecular fluorine laser system is further provided including a discharge tube filled with a gas mixture including molecular fluorine and a buffer gas, multiple electrodes within the discharge chamber connected to a discharge circuit for energizing the gas mixture, a resonator for generating a laser beam including a first line of multiple characteristic emission lines around 157 nm, and a power amplifier for increasing the power of the beam generated by the resonator to a desired power for applications processing. The resonator includes at least one line-narrowing optical component for narrowing a linewidth of the first line around 157 nm. The gas mixture has a total pressure which is sufficiently low such that the line-narrowed first line has a linewidth of less than 0.2 pm.
A molecular fluorine laser system is also provided including a discharge tube filled with a gas mixture including molecular fluorine and a buffer gas, multiple electrodes within the discharge chamber connected to a discharge circuit for energizing the gas mixture, a resonator for generating a laser beam including a first line of multiple characteristic emission lines around 157 nm, a gas handling unit coupled with the discharge tube for flowing gas between the discharge tube and the gas handling unit, a processor for controlling the flow of gases between the gas handling unit and the discharge tube to control one or more parameters associated with the gas mixture, and a power amplifier for increasing the power of the beam generated by the resonator to a desired power for applications processing. The gas mixture has a total pressure which is sufficiently low such that the laser beam includes the first line around 157 nm having a linewidth of less than 0.5 pm.
A molecular fluorine laser system is also provided including a discharge tube filled with a gas mixture including molecular fluorine and a buffer gas, multiple electrodes within the discharge chamber connected to a discharge circuit for energizing the gas mixture, a resonator for generating a laser beam including a first line of multiple characteristic emission lines around 157 nm, a gas handling unit coupled with the discharge tube for flowing gas between the discharge tube and the gas handling unit, and a processor for controlling the flow of gases between the gas handling unit and the discharge tube to control one or more parameters associated with the gas mixture. The gas mixture has a total pressure which is sufficiently low such that the laser beam includes the first line around 157 nm having a linewidth of less than 0.5 pm.
A method for controlling a bandwidth of an excimer or molecular fluorine laser system is also provided, including the steps of operating the laser system, monitoring the bandwidth of an output beam of the laser system, controlling a gas mixture pressure within a laser tube of the laser system at a predetermined pressure that is sufficiently low such that the output beam includes a first line of multiple characteristic emission lines around 157 nm having a linewidth of less than 0.5 pm, and amplifying the output beam for increasing the power of the beam generated by the resonator to a desired power for applications processing.
A method for controlling a bandwidth of an excimer or molecular fluorine laser system is further provided including operating the laser system, monitoring the bandwidth of an output beam of the laser system, and controlling a gas mixture pressure within a laser tube of the laser system at a predetermined pressure that is sufficiently low such that the output beam includes a first line of multiple characteristic emission lines around 157 nm having a linewidth of less than 0.5 pm.
A method for controlling a bandwidth of an excimer or molecular fluorine laser system is also provided including operating the laser system, and controlling a gas mixture pressure within a laser tube of the laser system at a predetermined pressure that is sufficiently low such that the output beam includes a first line of multiple characteristic emission lines around 157 nm having a linewidth of less than 0.5 pm.